My Patrol leaked oil between the gearbox and transfer case.
I removed the transfer case on Saturday and will replace both the gearbox seal and the t/case seal.
My question is: Should I use original Nissan seals or can I use aftermarket seals? I can get seals from Seal Centre in Pretoria.

After market seals will work well , but will only last for about 2 years . Rather spend the extra money to buy genuine seals if possible .
Why is the seal leaking ? Has the seal gone hard , or have the lips worn ?
A hard seal would indicate high gearbox temperatures . Worn lips would be from high mileage . If the lips are not worn , then you have a shaft with excess runout or wobble . It's nice to see you guys working on your own vehicles ! When all goes wrong in the bush , at least you have some idea of the workings of your vehicles .

The seals are in and the t/case is back in the car.
You have to do a bit of underthecar yoga to get to all the nuts and bolts but myself and Jack (that is trolley jack) managed to get it out and back in.
I also weighed the t/case and it is +-50kg wihout oil.

I Use Castrol Tansmax Z in the transfer case, which is a very high quality ATF but expensive at R 112 per 500 ml.
The owners manual states you can use Nissan Matic C or equivalent (Nissan Matic D) or API GL- 4 viscosity SAE 75W-90
Castrol Trans max Z is an approved Nissan Matic D ATF.